Nutrient learning, perception and generalization differ among wild pollinator species

Learning is the process through which skills, knowledge, behaviors are acquired and developed. Through life experiences, pollinator insects, learn to associate odor or visual stimuli from flowers with a rewarding food as pollen or nectar. This capability allows them to obtain resources efficiently and provides a valuable pollination service. Here, we compared the learning capability among different wild pollinator insects by mean of experiments based on the recent Free-Moving Proboscis Extension Response (FMPER) technique. Specifically, we evaluated the process of perception, learning and generalization between pollen enriched with different concentrations of fatty acid (which play a critical role in the survival, development and reproduction of many animals). We compared the associative learning in two castes of bumble bees (queens and workers of Bombus terrestris), honey bees (Apis mellifera), solitary bees (Ruizanthedella mutabilis) and non-bee pollinator species (the hoverfly Eristalis tenax). Our results reveal that learning performances differed among bumble bee social castes, with queens acquiring learning odorants more effectively than workers. Likewise, learning performances differed among the four species of insect pollinators. Honey bees acquired odor-sucrose association more rapidly than the other species. Likewise, bumble bees learned better than the solitary bee species and the hoverfly. The pattern of generalization among odorant stimuli as also different among the studied species, with honey bees showing stronger generalization and hoverflies showing more specific response patterns. Studying the learning behavior in insect pollinators provides valuable information for the conservation of these species and services they provide, through adapted pollinator-friendly schemes matching their behavioral performances.